diff --git a/src/clockinator.S b/src/clockinator.S
index 4b0edf5..a18dcec 100644
--- a/src/clockinator.S
+++ b/src/clockinator.S
@@ -1,10 +1,29 @@
-; Registers
-;   r16: ISR setup, reused only by START_BLINK on loop
+; Registers TODO: use .def for these!!!!
+;   r16: ISR setup (vct) -> timer0_set (main) -> START_BLINK (loop)
+;   r17: timer1_set (main) -> timer1_cnt low byte (loop)
+;   r18: timer1_set (main) -> timer1_cnt high byte (loop)
+;   r19:
+;   r20:
+
+
+.org 0x0000                 ; RESET Vector
+    rjmp    main
+.org 0x0002                 ; INT0 button interrupt (tap tempo)
+    ;rjump tap_tempo --> should have timer0_start --> if timer0_overflow_count=0 start timer (?)
+.org 0x0004                 ; TIMER0 overflow
+    rjump timer0_isr
+.org 0x0006                 ; TIMER1_COMPA
+    rjmp    timer1_isr
+.org 0x0012                 ; TIMER0_COMPA
+    rjmp    stop_blink
+
+.dseg
+    timer0_overflow_count: .byte 1
+
+.cseg
+    clr     r0
+    sts     timer0_overflow_count,  r0
 
-.org 0x0000                             ; RESET Vector
-    rjmp        main
-.org 0x000A                             ; TIMER0_COMPA (Timer0 Compare Match A)
-    rjmp        stop_blink
 
 #define __SFR_OFFSET 0
 #include <avr/io.h>